The present invention relates to a multipolar switch, such as a molded-case circuit breaker, including power supply-side and load-side polar terminals arranged adjacent to each other at front and rear sides of an insulated box, and in particular, to a terminal unit for increasing the insulation distance between the phases for the power supply-side terminals.
Conventionally, the insulation distance between the terminals is determined by the shapes of the case and cover forming an insulated box of a switch. That is, to increase the insulation distance between the terminals, the size of the interphase partition wall is increased, and to increase the insulation distance between a board panel on which the switch is mounted and the terminal, a panel cut surface of a cover, i.e. a top surface of the cover which contacts the board panel, is located higher than the terminal surface.
However, the required insulation distance varies according to the standards for the switches. Thus, the dimensions of the insulated box are conventionally determined so as to obtain a maximum insulation distance prevailing among the standards. On the other hand, it has been required to reduce the outside dimensions of the switch, and an insulated box smaller than that of the standard size is used for the application that does not require the maximum insulation distance. As a result, two types of the insulated boxes must conventionally be provided, depending on the required insulation distance.
It is thus an object of the present invention to reduce the size of a switch while allowing the insulation distance to be easily increased.
To attain this object, according to the present invention, a terminal unit having a greater insulation distance than a switch main body is installed in a multipolar switch including power supply-side and load-side polar terminals arranged at front and rear sides of an insulated box and adjacent to one another. The insulated box comprises a case, and a cover having a screw-tightening opening immediately above the polar terminals.
The terminal unit comprises polar connection conductors each having a connection section at one end connected to the terminal and a terminal section at the other end thereof to which an electric wire is connected, and an insulated housing for allowing the connection sections of these connection conductors to project outwardly and surrounding the terminal sections. An interior of the insulated housing is partitioned into wiring spaces for each pole by means of interphase partition walls. Each wiring space has a closed end from which the connection section projects, and a wire insertion port opened at an opposite end thereof. A wire passage is formed between the wire insertion port and the terminal section for guiding the electric wire. The insulated housing has a screw-tightening opening immediately above the terminal section, and is installed at the power supply-side end of the insulated box so as to cover the screw tightening holes in the case.
In this structure, it is possible to install the terminal unit having the insulation distance between terminals for the connected conductors and the insulation distance between the terminal and a panel cut surface appropriately determined based on the shape of the insulated housing in the insulated box of the switch, and to allow the insulation distance greater than that of the switch main body, as required.
Preferably, each connection conductor has a step such that its terminal section side is lower than its connection section side. Thus, the step serves to increase the insulation distance between the terminal and the panel cut surface.
Preferably, inclinations are formed in top and bottom wall surfaces of the wire passage to guide electric wires toward the terminal section. Thus, even if the wire passage is elongated to increase the insulation distance, the electric wires can easily be inserted into the terminal unit. Additionally, insulation distance can be effectively increased by forming multiple vertical grooves along the side wall surfaces of the wire passage.